Index shifter for bicycle transmissions

Abstract

An index shifter for a bicycle transmission, which index shifter is mounted on a part of a bicycle and has a casing, a locking element with notches which is connected to a rotary hand grip, and a winding drum for actuating a cable pull. The casing has a ring-shaped recess disposed therein, in which recess a detent spring is arranged. The detent spring is braced by two feet against the casing and has a lug which engages with the locking ring. Inside the casing is a casing projection with which one foot of the detent spring can be fixed to achieve a small amount of shift play. This permits small amounts of shift play, in particular for shifting hub gears on bicycles.

What is claimed is: 
     
       1. An index shifter for a bicycle transmission, said index shifter comprising: a housing to be disposed on a handlebar of a bicycle, said housing comprising a recess disposed therein;   said recess comprising a first sidewall and a second sidewall;   a ring element rotationally mounted within said housing to actuate a control cable of a bicycle transmission;   said ring element comprising a plurality of notches disposed therein;   a detent spring disposed within said recess of said housing and disposed between said first sidewall and said second sidewall;   said first sidewall and said second sidewall being disposed a distance from one another, said distance being sufficient to permit movement of said detent spring within said recess to provide shift play;   said detent spring comprising: a projecting lug disposed to alternately engage ones of said plurality of notches; and   a first end and a second end disposed opposite one another;     a projection disposed within said recess of said housing, said projection being disposed between said first end of said detent spring and said second end of said detent spring;   said projection being disposed as a limit stop for said first end of said detent spring;   said projection and said first side wall being configured to form a depression between them;   said first end of said detent spring being disposed in said depression between said projection and said first side wall;   said depression between said first side wall and said projection having a width extending between said projection and said first side wall;   said first end of said detent spring having a width extending between said projection and said first side wall;   the width of said depression being greater than the width of said first end of said detent spring; and   said projection, said first sidewall and said detent spring together being configured and disposed to limit movement of said first end of said detent spring in said depression to maintain a substantially constant play of said first end of said detent spring within said depression to provide a substantially constant shift play of said detent spring within said recess.   
     
     
       2. The index shifter according to claim 1 wherein said first end of said detent spring is configured to remain in said depression between said first side wall and said projection upon said projecting lug engaging any of said plurality of notches. 
     
     
       3. The index shifter according to claim 2 wherein a control cable is retractable into said index shifter against the biasing force of a transmission spring, and further wherein: said ring element is movable in a first direction of rotation and a second direction of rotation, said first direction of rotation being opposite to said second direction of rotation;   said ring element being disposed and configured to retract a control cable into said index shifter upon being rotated in said first direction of rotation; and   said ring element, upon being rotated in said first direction of rotation, being disposed and configured to transmit a force to said projecting lug, from said projecting lug of said detent spring to said first end of said detent spring, and from said first end of said detent spring to said projection.   
     
     
       4. The index shifter according to claim 3 wherein said housing comprises said projection. 
     
     
       5. The index shifter according to claim 4 wherein: said recess of said housing comprises a base portion extending between said first sidewall and said second sidewall;   said projection extending outwardly towards said detent spring from said base portion of said recess; and   said first end of said detent spring and said second end of said detent spring both being disposed immediately adjacent said base portion of said recess.   
     
     
       6. The index shifter according to claim 5 wherein said index shifter is configured for use with a hub bicycle transmission. 
     
     
       7. The index shifter according to claim 6 wherein: said detent spring comprises a first leg and a second leg, said first leg extending from said projecting lug to said first end of said detent spring;   said second leg extending from said projecting lug to said second end of said detent spring; and   said first leg being disposed at a substantial angle with respect to said second leg to form said projecting lug.   
     
     
       8. The index shifter according to claim 7 wherein: said ring element is rotatable with respect to said housing and said detent spring;   said ring element being disposed and configured to extend a control cable out of said index shifter upon being rotated in said second direction of rotation; and   said ring element, upon being rotated in said second direction of rotation, being disposed and configured to transmit a force to said projecting lug, from said projecting lug of said detent spring to said first end of said detent spring, and from said first end of said detent spring to said first sidewall.   
     
     
       9. An index shifter for a bicycle transmission, said index shifter comprising: a housing to be disposed on a bicycle, said housing comprising a recess disposed therein;   a ring element rotationally mounted within said housing to actuate a control cable of a bicycle transmission;   said ring element comprising a plurality of notches disposed therein;   a detent spring disposed within said recess of said housing, said detent spring being movable within said recess to provide shift play;   said detent spring comprising: a projecting lug disposed to alternately engage ones of said plurality of notches; and   a first end and a second end disposed opposite one another;     a projection disposed within said recess of said housing, said projection being disposed between said first end of said detent spring and said second end of said detent spring;   said projection being disposed as a limit stop for said first end of said detent spring;   a stop surface disposed adjacent said projection;   a depression in said recess formed by said projection and said stop surface;   said first end of said detent spring being disposed in said depression; and   said projection and said stop surface both being disposed to limit movement and provide a substantially constant play of said first end of said detent spring within said depression to maintain a substantially constant shift play of said detent spring within said recess.   
     
     
       10. The index shifter according to claim 9 wherein: said first end of said detent spring is configured to remain in said depression between said stop surface and said projection upon said projecting lug engaging any of said plurality of notches; and   said projection and said stop surface both being disposed to limit movement of said first end of said detent spring within said depression to maintain a substantially constant shift play of said detent spring within said recess.   
     
     
       11. The index shifter according to claim 10 wherein: said recess of said housing comprises a first sidewall and a second sidewall disposed a distance from one another, said distance being sufficient to permit movement of said detent spring within said recess to provide the shift play;   said detent spring being disposed between said first sidewall and said second sidewall; and   said first sidewall comprising said stop surface.   
     
     
       12. The index shifter according to claim 11 wherein a control cable is retractable into said index shifter against the biasing force of a transmission spring, and further wherein: said ring element is movable in a first direction of rotation and a second direction of rotation, said first direction of rotation being opposite to said second direction of rotation;   said ring element being disposed and configured to retract a control cable into said index shifter upon being rotated in said first direction of rotation; and   said ring element, upon being rotated in said first direction of rotation, being disposed and configured to transmit a force to said projecting lug, from said projecting lug of said detent spring to said first end of said detent spring, and from said first end of said detent spring to said projection.   
     
     
       13. The index shifter according to claim 12 wherein said housing comprises said projection. 
     
     
       14. The index shifter according to claim 13 wherein: said ring element is disposed and configured to extend a control cable out of said index shifter upon being rotated in said second direction of rotation; and   said ring element, upon being rotated in said second direction of rotation, being disposed and configured to transmit a force to said projecting lug, from said projecting lug of said detent spring to said first end of said detent spring, and from said first end of said detent spring to said first sidewall.   
     
     
       15. The index shifter according to claim 14 wherein: said ring element is rotatable with respect to said housing and said detent spring;   said housing being configured for being disposed on a handlebar of a bicycle;   said recess of said housing comprises a base portion extending between said first sidewall and said second sidewall;   said projection extending outwardly towards said detent spring from said base portion of said recess; and   said first end of said detent spring and said second end of said detent spring both being disposed immediately adjacent said base portion of said recess.   
     
     
       16. The index shifter according to claim 15 wherein: said detent spring comprises a first leg and a second leg, said first leg extending from said projecting lug to said first end of said detent spring;   said second leg extending from said projecting lug to said second end of said detent spring; and   said first leg being disposed at a substantial angle with respect to said second leg to form said projecting lug.   
     
     
       17. The index shifter according to claim 16 wherein said index shifter is configured for use with a hub bicycle transmission. 
     
     
       18. A method of operating an index shifter for a bicycle transmission, said method comprising the steps of: rotating a ring element having a plurality of notches within a housing of the index shifter;   alternately engaging a projecting lug of a detent spring with ones of the plurality of notches of the ring element and actuating a control cable of a bicycle transmission to shift the gears of the bicycle transmission;   moving the detent spring within a housing recess of the housing to provide shift play during said step of rotating;   positioning an end of the detent spring in a depression formed between a projection disposed within the recess and a sidewall of the recess, the projection being configured to serve as a limit stop for the end of the detent spring, the end of the detent spring having a width extending from the projection toward the sidewall, the depression having a width extending from the projection toward the sidewall, and the width of the depression being greater than the width of the end of the detent spring; and   limiting movement of the detent spring within the housing recess and maintaining a substantially constant play of the end of the detent spring within the depression with the projection disposed within the recess, the detent spring and the sidewall disposed adjacent the projection to maintain a substantially constant shift play of the detent spring within the housing recess.   
     
     
       19. The met hod according to claim 18 wherein: the end of the detent spring is a first end, the detent spring has a second end disposed opposite said first end; the ring element is movable in a first direction of rotation and a second direction of rotation, the first direction of rotation being opposite to the second direction of rotation; said method further comprising the steps of: rotating the ring element in the first direction of rotation and retracting a control cable into the index shifter against the biasing force of a transmission spring; and   said step of rotating comprising transmitting a force from the ring element to the projecting lug, from the projecting lug to the first end of the detent spring, and from the first end of the detent spring to the projection.   
     
     
       20. The method according to claim 19 wherein: the sidewall is a first sidewall, the recess in the housing has a second sidewall disposed a distance from the first sidewall, the distance being sufficient to permit movement of the detent spring within the recess to provide the shift play; said method further comprising the steps of: rotating the ring element in the second direction of rotation and extending a control cable out of the index shifter with the assistance of the biasing force of a transmission spring; and   said step of rotating comprising transmitting a force from the ring element to the projecting lug, from the projecting lug to the first end of the detent spring, and from the first end of the detent spring to the first sidewall.